In heavy-duty and performance-car use it is known to carry on a single pivotal arm assembly a pair of generally identical wiper blades each comprising a flexible elastomeric strip, a metallic backing, and a pivot extending transversely of the strip and back. Thus the wiper motor shaft carries a base on which are pivoted two inner arm supports which carry respective arm bars having outer ends that carry the respective wiper blades. The motor oscillates the base about an axis generally perpendicular to the portion of windshield being wiped, and the two supports are pivotal on this base about an inner axis generally parallel to the windshield, offset from the base axis, and lying in a plane perpendicular to this base axis. Respective springs urge the supports rotationally on the base about the inner axis in a direction pressing the wipers against the windshield. The wipers are in turn pivotal on the outer arm-bar ends about outer axes generally parallel to the inner axis or axes.
The windshield is invariably curved so the two wipers must be able to move independently at least limitedly to follow the windshield. Thus the two supports are either placed next to each other on a common pivot pin on the base and have separate springs spaced apart parallel to the inner axis, and the two arm bars are spaced apart somewhat axially of the inner axis and extend generally parallel to each other and radially from the inner axis from the outer end of the support. It is also possible to interleave the two supports, which makes providing the respective springs fairly complex, and which normally leads to the two parts rubbing and interfering with each other.
The disadvantages of these arrangements is that they are relatively complex and bulky. They block the view past the wiper assembly, and often do not allow proper independent wiper action.